Wednesday, February 8, 2012

We-Design-Day: Home Evaluation - Walls & Foundations

Last week, we started exploring how to assess the building envelop for our home evaluation. This week, we're going to look at our walls, what covers them and our foundations. It's a lot to cover, so let's get cracking!

The exterior walls work to protect the interior, give aesthetic value and support your home. Like the roof, they are exposed all the time to the elements. I want to introduce the wall and what's it made of. Think of your walls like a sandwich; the house's outermost layer is a water and weather resistant material – brick, vinyl or metal siding or stucco. It covers all the layers underneath. Immediately beneath that is an air barrier (like Tyvek) covering the sheathing over the studs. Commonly, oriented strand board is used (OSB is a building material that is composed of chips of wood adhered together in a crisscrossed pattern with wax and resins). Beneath this sheathing are the framing members – by law in my province, all exterior wall must be 2”x 6” structural wood members, however, 2” x 4” members are commonly used in other provinces and in the United States. Between the wood members is insulation – generally fibreglass batts however, spray foam insulation is also becoming more commonly used. On the first layer on the interior, next would be a moisture barrier (commonly a 6mil plastic that is stapled to the wood members and then taped with special tape to seal seams and holes. On the interior a 5/8” sheet of gypsum board is used (this replaced the lath and plaster method from the 1950’s). Figure 1 provides an idea of all the layers of the wall and the foundation.

Evaluation the condition of the exterior walls is tricky because so much of the wall is “covered” and we are unable to see it. Let’s start on the inside of your home. All the outside walls should be checked for:

Figure 1
  • Cold zones 
  • moisture or mould
  • soft spots
  • Other signs of damage or wear (this could include teeth marks or scratches – although not an issue where I live, termites, raccoons and other “vermin” can get in the covered spaces of our home and cause significant damage and can pose a health risk.

Pay special attention to areas around windows and doors (or other penetrations like milk doors or mail slots). Although signs of damage around these areas may indicate a failure in the window or door, it may also indicate issues with the siding or even parts of the roof.

So what happens if you find a cold zone? Does ice or moisture form? Is it always cold? Any drafts or air movement (try the tissue test or candle test)? Cold zones and moisture trapping can also be caused by air not circulating properly around a room. Blocked heat ducks, furniture and drapery can all affect how the air moves in your home.

Ensure furniture has “breathing” room – don’t push anything right up against any wall – especially an exterior wall. If moving furniture or drapery off of air ducts, away from cold air returns and away from walls doesn’t improve the problem, what’s next? Traditional batt insulation can settle over time, thus leaving the exterior walls inefficiently insulated and can allow the cold air to permeate the building. This will increase your energy bills and decrease your home’s energy value. It would be prudent to consult a professional to get a more comprehensive estimate and evaluation.

If you find mould, it is important to not disturb it and find an independent company to collect and test the mould. 

Next we’ll look at the exterior of your home. The one thing that is universal is the grade: the way the ground slopes away from your home. The earth should always slope away and towards the street. This is especially important because having it slope towards your home can lead to water entering your basement, crawl space or foundation and it will erode the earth that supports your home and cause cracking in your foundation. 

There are specific calculations and formulas to define the slope that is necessary. Butting a patio or concrete walkway up against your foundation can also lead to trouble (even though it is commonly done) because if you don’t allow enough of a slope, water will pool and cause issues.

Going into your basement to look at the walls and cement floor will be the place to start. Staining, white deposits and cracks are what to look for. If the basement gets damp or water infiltration during rain, there are likely more problems than you'll be able to see. Additionally, check the corners of your basement for signs of sinking  or dips. Foundation problems are best left to professionals - assessments and repairs!

We're making progress with our evaluation but we've still got more work ahead of us! Thanks for stopping in and come back next week as we work more on our evaluation!

Further reading:

Good info on home maintenance 


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